130 THE CANADIAN NATURALIST. [Vol. X. 



whilst between Oakville and Toronto, the rocks of the latter 

 age appear at the surface of the country. 



Those members of the Silurian foriiiMtion which are exposed 

 in the region under consideration belong to the Medina, Clinton, 

 and Niagara epochs. The best localities for making geological 

 examinations are at Thorold, Grimsby, Hamilton, Dundas. 

 Limehouse Station (G.T.R.) and Rockwood. Nowhere in East- 

 ern America are there better exposures of the various rocks of 

 this age, though in some localities, especially in the Western 

 States, the fossils are in a better state of preservation. How- 

 ever, in the above localities there is a very great difference in 

 the preservation of the fossils found, and nearly 200 species of 

 organisms can be procured from a limited number of localities. 

 A considerable variation of texture is observed in the rocks in 

 the different places, and although the number of species of animal 

 remains is considerable, yet owing to the crystalline texture of 

 the limestones, one is rewarded with meagre returns for his day's 

 labor. 



As we will see further on, the rocks under consideration are 

 intermediate in character between those of the State of New 

 York to the eastward, and those of Ohio to the westward, being 

 more calcareous than their equivalents in the former State, and 

 more argillaceous than those in the latter. 



In the study of the various rocks of the Niagara group, I have 

 examined the microscopical structure, and have made a number 

 of chemical analyses. At the end of the present paper there will 

 be found a catalogue of all the species of fossils in my own col- 

 lection, with some few that have been obtained by others, but 

 of which I have not been fortunate enough to obtain specimens. 

 This will be found to be the fullest catalogue of Canadian fossils 

 from the Niagara group yet published. 



Again, a few minerals are procurable at various localities from 

 cavities in the Niagara limestones, as well as mineral waters from 

 several natural springs and artificial openings, all of which will 

 be noticed in their proper places. 



As no part of the Province affords a greater variety of interest 

 to the student of geology than the region about the western end 

 of Lake Ontario, I will endeavour to a'ive a full but concise 

 account of those features and objects of attraction that will assist 

 the geological observer and student in the pursuit of this most 

 attractive and useful study of Nature. 



